[llvm] [TableGen] Check for duplicate register tuple definitions. (PR #95725)

[Jason Eckhardt via llvm-commits]

nvjle wrote:

Any comments on this tiny patch? It is almost NFC, but it does do more specific error checking, so I'm treating it as a functional change for good measure. The failures are not due to this patch.

https://github.com/llvm/llvm-project/pull/95725